April 8, 2017 3:05 am

By AGENCE FRANCE PRESSE, Stockholm, Sweden, Apr 7 – A massive manhunt was underway for the driver of a stolen truck that ploughed into a crowd outside a busy department store in central Stockholm Friday, killing four and injuring 15, Swedish police said.

A national police chief, Stefan Hector, said the police’s “working hypothesis is that this is a terror attack.”

One man was arrested in connection with the attack but the driver remained at large, police said.

According to the Aftonbladet newspaper, the arrested man is a 39-year-old of Uzbek origin and a supporter of the Islamic State (IS) group.

European politicians expressed solidarity, with European Commission President Jean-Claude Juncker saying that it was an “attack on us all.”

A spokesman for German Chancellor Angela Merkel said: “Our thoughts go out to the people in Stockholm, to the injured, their relatives, rescuers and police.

“We stand together against terror.”

US State Department spokesman Mark Toner said Washington was ready to provide any help it could to investigate “this brutal and senseless attack”.

“Attacks like this are intended to sow the seeds of fear, but in fact they only strengthen our shared resolve to combat terrorism around the world,” he added.

– Trucks as weapons –

It followed a string of similar attacks in Europe by people using vehicles as weapons.

The deadliest came last year in France on the July 14 Bastille Day national holiday, when a man rammed a truck into a crowd in the Mediterranean resort of Nice, killing 86 people.

Last month, Khalid Masood, a 52-year-old convert to Islam known to British security services, killed five people when he drove a car at high speed into pedestrians on London’s Westminster Bridge before launching a frenzied knife attack on a policeman guarding the parliament building.

And in December, a man hijacked a truck and slammed into shoppers at a Christmas market in Berlin, killing 12 people.

In 2014, IS called for attacks on citizens of Western countries and gave instructions on how they could be carried out without military equipment, using rocks or knives, or by running people over in vehicles.

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